Some suggestions for the Contributors page

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>
Tweak to CONTRIBUTING.rst

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>
Fix comment in src/mongo/client/gridfs.h

When loading from a string rather than a file, remoteName is not optional

Signed-off-by: Matt Kangas <matt.kangas@mongodb.com>
Fixed jstest comment per old pull request
SERVER-11277 cleanupOrphaned does nothing on empty shard